Gear pump



Sept. 19, 1933. L, EDWARDS 1,927,395

GEAR PUMP Filed Nov. 13, 1931 3 Sheets-Shea?l 1 zz INVENTOR CttornegSept. 19, 1933. l l EDWARDS 1,927,395

GEAR PUMP Filed Nov. 13, 1931 3 Sheets-Sheet 2 nventor L. L Edwards'Sept 191 L. EDWARDS 1,927,395

GEAR lPUMP 'v Filed Nov. 15, '1931 5 vSheets-Shea?, 5

rwentor L' L Erdwa/rd APatented Sept. 19, 1933 PATENT OFFICE 1,927,395GEAR PUMP Leonard L. Edwards, Longview, Wash.

Application November 13, 1931 Serial No. 574,890

8 Claims.

This invention is directed to an improvement in gear pumps with a viewto providing certain details of construction tending to increase thelife of the pump as a Whole and simplify the renewal or adjustment ofparts necessarily subjected to wear in the operation of the pump.

The primary object of the present invention is the provision of linersfor the pump chambers, with the liners in separable meeting sections,such liners being arranged to completely cover the inside of the pumpchambers and protect the housing from Wear of any kind incident to theuse of the pump.

A further object of the invention is the correlation of the liners ofeach pump chamber, so that it may be readily reduced in axial dimensionin the event of wear, together With the provision of means forautomatically maintaining the liners in proper relation to the pumprotor.

A' further object of the invention is the provision of means by whichthe means for automatically maintaining the liners in proper relation tothe pump rotor is utilized to provide in effect arrelief valve for thepump when the pump has reached a given pressure.

A further object of the invention is the provision of a packing nutwhich is held in perfect alignment with the shaft when the nut has beenhacked oli' for the insertion of new packing, thereby avoiding the looseposition of the nut in ordinary structures when backed oli for theaddition of packing, and materially simplifying the reapplication of thenut in shaft packing relation.

The invention is illustrated in the accompanying drawings, in which:

Figure 1 is a view in elevation of the pump.

Figure 2 is a section longitudinally of the pump, the line of sectionpassing through one of the pump rotors.

' Figure 2a is a section on the line 2a-2a, Fig. 2.

Figure 3 is a perspective View of one of the half liners.

Figure 4 is a perspective view of the pump housing.

Figure 5 is a perspective view of one of the packing nuts.

Figure 6 is a broken vertical sectional View, showing one means forholding the reconstructed liner sections against axial movement.

Figure 7 is a similar View showing a modified means for holding thereconstructed liner sections against axial movement.

Figure 8 is a similar view showing a further modied means for holdingthe reconstructed liner sections against axial movement.

The pump is made up of a pump housing 1 having upper and lowerintersecting circular rotor chambers 2 and 3, these chambersintersecting in the central plane of the housing to form the usualopening through which the pump rotors may cooperate. inlet 4 and anoutlet 5 in line with the intersection of the pump rotors, these detailsbeing the usual conventional construction.

Each end of the pump housing is provided with a removable end housing at6 and 7, these housings being of identical construction and eachincluding a cover plate 8 designed to directly bear against the end ofthe pump housing and close the latter except for the shaft openings 9 insuch plates. Each end housing includes a roller bearing carrier plate 10secured in spaced relation to the cover plate by webs 11.

A gear housing 12 is removably secured to the carrier plate 10 of oneend housing, as 6, this gear housing being formed with an opening 13 forthe extension of one of the pump rotor shafts for driving provisions, asuitable bushing or bronze bearing 14 being employed. The opposite endhousing 7 is provided With a cover plate 15 conforming to the generaloutline shape of the pump housing.

The end housings 6 and 7 are secured to the pump housing by bolts 16passing through the respective housings, having heads at one end andnuts at the opposite end to maintain a iuidtight connection, while thegear housing 12 and cover plate l5 are secured to the bearing carrierplates 10 by suitable bolts and nuts 17.

The pump rotor gears 18 and 19 are arranged in the respective rotorchambers 2 and 3 and scoured upon shafts 20 and 21 to provide for thenecessary pumping cooperation of the gears. These shafts pass throughthe openings 9 in the cover plates 8 and openings 22 in the rollerbearing carrying plates 10, the shafts being provided with cooperatingdriving gears 23 in the gear housing 12, with one' of the shaftsextending through the opening 13 for driving purposes, the opposite endsof the shafts extending into the cover plate 15.

Each opening 9 in each cover plate 8 is formed on the side next thebearing carrier plate 10 to provide a packing seat 24, the cover plateon the side next the plate 10 having an integral annular extension orWall 25 concentric With the shaft opening 9 but of greater diameter thanthe diameter of such opening to provide for the reception of the packingabout the shaft for guiding the The housing is formed with an A packingnut for the proper compression of such packing.

The openings 22 in the roller bearing carrier plates are, at the endnext the housing 12 and cover plate 15, of sufficient diameter toreceive and support ball bearings 26 through which the shafts and 21pass, the plates 10 being thickened concentric with the opening to pro'-vide for the ball bearing reception and to fur,- ther provide forreceiving and support packin nuts 27.

These packing nuts, as shown more particularly in Figure 5, arecentrally formed with an opening to more or less accurately permit thepassage of the shafts 2O and 21 and include a packing section 28 havinga diameter to accurately fit within the wall 25, with such section 28formed with openings 29 by which the packing nut may be adjusted.

Each packing nut 'also includes a circumferentially enlarged section 30,integral, of course, with the section 28, which section 30 is exteriorlythreaded at 31 to cooperate with threads 32 formed in the enlargement 33supporting the ball bearing, the surface formed of the threads 32 beingof somewhat less diameter than the opening receiving the ball bearingand thus providing for the complete removal or insertion of the packingnut when necessary and also forming a shoulder 33' against which theball bearing race outer ring bears to position the ball bearing. Thispacking nut arrangement provides an important detail of the presentinvention which will be more specifically referred to hereinafter.

The important detail of the invention is the provision of linersarranged to substantially encircle the pump gears on rotors andproviding a removable and readily replaceable element which will take upwear incident to the use of the pump and also provide an automaticrelief for the pump when the pump pressure has reached a given point.These liners, as shown more particularly in Figure 3, are made up ofduplicate sections, each including an end wall 34, the periphery ofwhich is accurately machined to rit a corresponding rotor chamber, andside wall extending inwardly from the end wall at the periphery thereofand concentric with the rotor chamber.

Each liner is made up of two such sections assembled with the free edgesof their side walls 35 in contact, with their end walls 34 closelycooperating With the sides of the pump gears and the side wallsconcentric with such gears to define the uid space necessary in thepumping operation. The end walls 34 are interrupted at the meeting lineof the rotor chambers, so that when the liners are assembled in therespective chambers. these interrupted or plain portions 36 of the endwalls of respectively similar liners are in contact.

The side walls 35 of each liner are cut away adjacent the plain portions36, as at 36', so that when the sections of the upper and lower linersare in proper position in the rotor chambers, an opening is provided bythe interruptions of the side walls of the liners substantiallycorresponding to the inlet and outlet openings, obviously providing forthe now of uid.

It will thus be plain that each pump gear or' rotor is. exceptthroughout their meshing area and in correspondence with the inlet andoutlet openings of the housing, completely enclosed by the liners andthat the liner of each pump rotor is made up of two sections, movablerelatively in opposite directions either for separation or application.The liners obviously provide a wear element for the pump rotors andthus, under such wearas will interfere with proper pump operation,.theliners may be removed and the Wear compensated for, as will laterappear, or following the limit of such compensation, the liners may bereadily replaced by new liners. In any event, the pump housing which, ascompared with the liners, is the expensive and material element,is'protected from wear by the liners and thus the life of the housing sofar as pump Wear is concerned is indefinite.

If the end walls 34, which is the detail subjected materially to wear,become worn to an extent to interfere with pump operation, the linersections are simply removed and the free edges ofthe side walls 35 filedaway to the desired extent, so that when the liner sections arereplaced, the end walls 34 of the sections of a particular liner will bepermitted to approach each other more closely to compensate for thepreviously worn condition and serving in this manner to restore the pumpto normal operation so far as the wear of the pump rotors is concerned.

Normally, the liners including the thickness of the end wall 34 and theaxial length of the side wall 35, are such that when the liners are inplace, the relatively outer surface of the end wall 34 is in line withthe ends of the pump casing, so that the cover plates 8, when in appliedposition, serve to hold the liner sections xedly against axial movement.By cutting away the free edges of the side wall 35 to compensate forwear, it will of course be apparent that when such reconstructed linersections are replaced, the outer sections of the end walls will beinwardly of the normal holding surfaces of the cover plates 8 and inorder to hold the liners in proper position against relative axialmovement, several means are.pro posed.

Disregarding for the moment an additionally material function of one ofsuch ways as will later more specifically appear, it is apparent thatconventional shims 37 may be placed between the cover plates 8 and theend walls of ythe liner sections to provide the necessary contactbearing, such, for example, as illustrated in Figure 6. Another meansfor accomplishing this result is through the medium of set-screws 38threaded through the cover plates 8 and bearing on the end walls 34 ofthe liner sections to hold the reconstructed liner sections againstaxial movement.

The preferred method of accomplishing this result, however, is shownmore particularly in Figure 2 and in a slightly modified form in Figure8. This preferred means, as shown in Figure 2, consists in a coil spring39 arranged to encircle the shafts 20 and 21, of course in spacedrelation thereto, and seating at their respective ends in appropriaterecesses 40 formed in the outer surfaces of the end walls of the linersections, and, if desired, similar recesses formed in the end plates 8,though the latter are not essential.

In Figure 8, a slight modification of this arrangement is shown, whereinthe compensating member is formed by a series of small springs 41interposed between the end wall 34 of the liner section and the coverplate, the ends of the springs being preferably seated in recesses 42 inboth the liner section end walls and the cover plate.

The preferred method proposed for compensating for the relativelyreduced axial length of the liner incident to cutting laway the sidewalls to take up wear is, of course, automatic in its action, as thesprings act normally to maintain the free edges of the liner sections incontact, but as the holding means is thus resilient, an importantfunction in connection with the pump proper is provided for. Thesesprings, either in the form shown in Figure 2 or in the form shown inFigure 8, will yield to permit relatively opposite axial movement of theliner sections making up a liner or an axial movement of one of saidsections relative to the pump rotor. As the strength of these springscan, of course, be predetermined, it naturally follows that the pressureon the inner surface of the end wall of the liner section at which thespring will yield may be set.

As the liner sections, or one of them, will yield axially under pumppressure unless prevented and as the preventing means is incident to thesprings, the 'force of which may be determined, it follows that at apredetermined pump pressure, as regulated by the strength of thesprings, the liner sections, or one of them, will yield axially torelieve this pressure or to prevent an excess pressure within the pump.Therefore, the spring means for compensating for the reconstructed linersections as described also permit the liner sections to serve as anautomatic relief valve, as will be apparent. This is particularlyadvantageous when pumping heavy oils, for example, due to the fact thatthe-section of the pump is affected in proportion to the discharge thatis being returned and with proper regulation of the predeterminedeffective pressure of the pump, it is apparent that it is not necessaryfor the pump to draw its full capacity and suction and overow that whichis not being used from the discharge side.

The liner sections, therefore, provide a means for completely protectingthe pump housing against wear. The liner sections are further arrangedin such correlation that by the simple operation of cutting away thefree edges of their side walls, they can be made to compensate, for aconsiderable period, for the wear incident to the operation of the pumpand ordinarily affecting the end walls of such sections. Furthermore,the liners are held in position preferably through the medium of meanswhich will permit the liner sections to act as `automatic relief valves,with the relief function set at any predetermined pressure within thelimits of the pump.

Of course, it is to be understood that, while the use of the springs hasbeen described primarilyas a'means for holding the liner sections inplace when such sections Yhave been adjusted to compensate for wear, thefunction of the automatic relief feature is'not to be understood asapplicable only to the liner sections following their reconstruction tocompensate for wear.

The liner sections as originally applied may have their end walls 34 ofsuch relative thickness that they will not be held through directcontact with the cover plates 8 and under these conditions the springs39 or 41 may be employed from the very inception of the construction.Thus, the automatic relief function provided by the liners will beeffective whether the liners are in their original condition or in theirreconstructed condition to compensate for wear. Thus, it will beunderstood that a salient feature of the invention is the utilization ofliners made up in sectional form which not only protect the pump housingfrom wear but in themselves provide automatic at all times in threadedcooperation with the wall 25 and that when it is desired to apply newpacking, the nut is simply threaded into the enlargement 33 so that thefree end of the packing section 28 is suflciently removed from the endof the wall 25 to permit the introduction of new packing. After thepacking has been inserted, the packing nut is simply advanced tocompress the packing, remaining at all times in cooperation with theenlargement 33 through the threads 30 and 31. The nut is thus held inperfect alignment with the shaft, the usual diculty of applying theconventional wholly separated packing nut is entirely avoided, and themere turning of the nut through the use of a` suitable tool cooperatingwith the openings 29 provides for either relieving the packing orcompleting the packing compression in a simple and expeditious manner.

What is claimed as new is:

l. A gear pump including a pump housing having gear chambers, a linerfor each chamber substantially enclosing the gear therein, said linerbeing made up of independent wholly disconnected sections, a cover platefor closing the ends of the gear chambers, and springs intermediate thecover plate and each liner section to maintain pressure on the sectionstoward each other in an axial direction, said springs permitting axialyielding of the sections at predetermined pumping pressure to cause theliner sections to function as a relief valve.

2. A gear pump including a pump housing formed with gear chambers, pumpgears operating in the chambers, a sectional liner substantiallyenclosing each pump gear, the liner of one chamber having bearingcontact relation with the liner of the other chamber to prevent rotativemovement of the liners, each liner being made up of two whollydisconnected sections each comprising an end wall and a side wall, theside walls of the sections having edge contact and being interrupted toprovide for the inlet and outlet of the fiuid, a cover plate closing theends of the gear chambers, and springsintermediate each cover plate andeach liner section.

3. A gear pump including a pump housing formed with gear chambers, pumpgears operating in the chambers, a sectional liner substantiallyenclosing each pump gear, the liner of one chamber having bearingcontact relation with the liner of the other chamber to prevent rotativemovement of the liners, each liner being made up of two whollydisconnected sections each comprising an end wall and a side wall, theside walls of the sections having edge contact and being interrupted toprovide for the inlet and outlet of the fluid, a cover plate closing theends of the gear chambers, and springs intermediate each cover plate andeach liner section, said springs maintaining the free edges of thesections of the liner in contact and permitting separation of such edgesunder predetermined pump pressure to function as an automatic reliefvalve.

4. A gear pump including a pump housing, cooperating pump gearsoperative therein, a liner substantially enclosing each pump gear andmade up of two wholly disconnected sections having a median linesubstantially at the circumferential median line of the gear, and meansfor permitting axial movement of at least one section of each liner toprovide for automatic relief of the pump pressure.

5. A gear pump including a pump housing, cooperating pump gearsoperative therein, a liner substantially enclosing each pump gear andmade up of two wholly disconnected sections having a median linesubstantially at the circumferential median line of the gear, and meansfor permitting axial movement of at least one section of each liner toprovide for automatic relief of the pump pressure, said means beingvariable to predetermine the pump pressure at which the liner sectionacts as the relief valve.

6. A gear pump of the type including a housing and cooperating gearsoperative within the housing, said pump including a two-part liner foreach gear, the respective parts of the liner for each gear being free ofconnection with each other and with the housing or with the parts of theliner of the other gear, the respective parts of the liner of each gearhaving relatively straight edges for cooperation with similar edges ofthe liner of the other gear when -the liners are in applied position toprevent independent rotative movement of the liners, a portion of eachliner part of each gear being cut away to provide,

when the liners are assembled, an uninterrupted passage through theliners coincident with the cooperating plane of the gears.

7. A liner to be arranged between the gears and housing of gear pumps,each liner being made of two parts including a wall to overlie the sideof the gear and a flange to partly overlie the periphery of the gear,the Wall terminating in a straight edge and the ange being cut awayadjacent such straight edge, the liners for one gear together enclosingsuch gear except through' the area dened by the cut away portions of theflanges.

8. A two-part liner for the gear of a gear pump, each liner partincluding a side wall to overlie the side wall of the gear, and alateral flange to overlie approximately one-half of the width of theperiphery of the gear, the free edges of the flanges abutting when theliner parts are in position, the side walls terminating in a straightedge and being formed with an opening for the passage therethrough ofthe shaft of the gear, the lateral ange of each liner being cut awayadjacent. the straight edge of the side Wall to present, when the linerparts are assembled in relation to the gear, an opening in the line ofthe operative plane of the gear.

LEONARD L. EDWARDS. [L.S.]

